Condenser



y 30, 194% J. A. FLANZER I 2,209,546

CONDENSER Filed Dec. 5, 19 58 2 Sheets-Sheet 1 e- IIIIIIIIIIIII'ATTORNEY INVENTOR Jose-AVA RAM Z5? 1940- J. A. FLANZER 2.209.546

CONDENSER Filed Dec. 3, 1.938 2 Sheets-Sheet 2 INVENTOR JOJP/l 4.fzmvzzp BY MK AMA-444 A'ITORNEY Patented July 30, 1940 UNITED STATESPATENT OFFICE 2,209,546 CONDENSER.

York

Application December 3, 1938, Serial No. 243,757

20 Claims.

This invention relates to condensers, and more particularly to so-calledtrimmer condensers for radio and similar purposes. The primary object ofmy invention is to generally improve such condensers. I

The conventional trimmer condenser comprises metal plates riveted oreyeleted at opposite ends of an insulation base, said plates beingextended to form lugs for soldering. The top plate is so shaped as totend to move upwardly, and it is drawn down by means of an adjustingscrew passing through the plates and base. Considerable difficulty hasarisen because of the effect of bending the extension or soldering lugformed on the plate. This may be bent, either intentionally, oraccidentally by a workman soldering a connection to the lug. Outwardbending of the lug tends to bend the top plate downwardly so that it nolonger springs upwardly as it should when pressure of the adjustingscrew is relieved. This sharply reduces the range of adjustment of thecondenser and may completely spoil the same for its intended purpose.

One object of my invention is to overcome the foregoing difiiculty. ThisI do by extending the top plate not only downwardly along the edge ofthe base, but also inwardly beneath the bottom of the base. Thisinwardly bent bottom portion is eyeleted to the base while the top plateis left entirely free of the base. A soldering lug is struck from thetop plate to a point immediately adjacent the eyelet at the bottom ofthe condenser, and this lug is bent outwardly and downwardly away fromthe base. The. result of this construction is that the eyelet holds theplate at the weakest point of the soldering lug, and bending of the lugis arrested at the eyelet and is incapable of moving the top plate. Theconnection of the lug is solely to the inturned bottom part of theplate, and that part of the plate is locked in position by the eyelet. Afurther advantage of this new construction is that there is a reductionin the length of the blank from which the plate is formed. Hence, thereis considerable saving in metal cost, because the metal is preferablyphospher-bronze for permanent resilience.

As so far described, the invention is applicable to a simple two-platetrimmer condenser, but of late, a demand'has arisen for multiplate platetrimmers of greatly increased capacitance. and further features andobjects of my invention center about such multiplate plate trimmercondensers. In some condensers extra plates have been added beneath thetwo original main plates, but this prevents proper opening up of theplates. and

while producing a desired maximum capacitance, does not produce a largerange of capacitance, for it is impossible to get down to a low minimumcapacitance. In accordance with my invention, only the top plate is athick plate. All of the remaining plates are made of exceedingly thinresilient metal. Moreover, these plates, or all except the bottom plate,are preferably curved or bowed upwardly so that the plates tend to openout. Thin sheets of mica, or so-called films, are disposed between theplates, and in accordance with a further feature of the presentinvention, these films are eyeleted to the base at only one end,alternate films being eyeleted at the opposite ends of the condenser. Inthis way, the films do not prevent bowing or upward spreading of theplates, except insofar as they resist bending. This resistance is smallbecause the mica films are made particularly thin, say, only half thethickness of the metal plates. The straight films being disposed betweenthe curved plates, the films help produce a wide opening or spread ofthe plates, but the films are not thick enough to prevent some necessarybending at the eyelets during opening of the condenser.

As so far described, the condenser might be initially open, yet mightnot return to fully opened position after being screwed up tight toclosed condition. The reason for this is that the free edges of one setof plates may sometimes tend to become wedged into the other plates nearthe eyelet holding the latter plates together. When the condenser isscrewed up tight, the plates tend to become bound together and do notopen up freely when the adjusting screw is released. Thus, a desired lowminimum capacitance may not be obtained after the condenser has beenadjusted to maximum capacitance. Moreover, the condenser should besubstantially insensitive to temperature change. With the condenser asso far described, there is little or no change in temperature when thecondenser is screwed up tight, but substantial changes of capacitancewill result from temperature changes when the condenser is partially orfully open.

A further object of the present invention is to overcome the foregoingdifficulties. This may be done by the introduction of spacing means atthe eyelets to space apart the plates at the eyelet. I prefer to useinserted strips of metal or spacers, these preferably being thicker thanthe metal plates and mica films. The spacers are preferably disposed atthe free ends'of the plates and films, and successive spacers aresecured at opposite ends of the condenser. These spacers preventcatching or wedging of the ends of the plates between the surroundingplates, and thus facilitate full opening of the condenser. They alsoproduce an initial spacing which itself helps opening of the condenserto a small minimum capacitance. This initial spacing does not preventclosing under the extreme pressure produced by the adjusting screw, andthe plates bend downward slightly to attain full closing or maximumcapacitance. Temperature response is minimized, and the condensers maybe brought to an accuracy of, say, one per cent, instead of, say, tenper cent, in respect to variation with temperature. The spacers increasethe range of capacitance adjustment of the condenser by lowering theminimum capacitance for a condenser having a predetermined maximumcapacitance.

Still another object of the present invention concerns the mounting of aplurality of IihflCOIldensers on a common mounting strip. Heretofore,the condensers have been assembled to such a strip as a part of theregular eyeleting or manufacturing operation. The condensers have neverbeen completed except as mounted on the strip. This makes it difficultto fill orders quickly. It results in numerous rejections. for a defectin one condenser causes a rejection of the assembly of condensers. Theentire strip of condensers must be handled through all of themanufacturing operations, and this makes the manufacture highly variableand non-uniform, for the strips are different in length, may differ inmaterial, and have different numbers of units mounted thereon.

A further object of the present invention is to overcome the foregoingdifiiculties and to provide a new, simple, and extremely inexpensivemeans for mounting individual and previously completed condensers onastrip. For this purpose, I provide an inexpensive sheet metal staplewhich is secured to the base of the condenser by means of the regularbushing which is anyway provided for the adjusting screw. The condensersare handled as single units throughout all manufacturing operations.Jigs and dies may be provided and set up to properly handle the singleunits. These units may be made up and kept in stock, the units havingdifferent numbers of plates ranging from, say, two to seven. When ordersare received, the appropriate units are quickly and readily assembled onstrips in accordance with the requirements of the customer. Theserequirements may differ as to the number of condensers and may alsodiffer as to the num ber of plates in each of the battery of condenserson the strip. Such highly variable requirements are readily fulfilledwhen, as in the present case, the condensers are made up separately andare assembled on strips only after orders are received. If a unit failsunder test and is rejected, only that unit or condenser is rejected andnot a whole battery of condensers. For example, there is a very severebreakdown voltage test which causes, say, five per cent rejections.With, for example, five condensers on a strip, the old practice wouldincrease the percentage possibility of rejection from, say, five percent, to twenty-five per cent, for any one of the five units on thestrip may break down. The highly competitive conditions under whichthese condensers are made would make it prohibitive to use screws,bolts, or any screw machine parts for attaching individual condensers toamounting strip. The staple of the present invention, however, isinexpensive,

and the condenser is attached to the strip bya single movement of acomparatively small hand-press or foot-press which bends the ends of thestaple. The staple may be opened to replace a condenser, if a finalbreakdown voltage test; is performed after assembly of the units on a stp.

To the accomplishment of the foregoing and such-other objects as mayhereinafter appear, my invention consists in the condenser elements andtheir relation one to the other, as hereinafter are more particularlydescribed in the specification and sought to be defined in the claims.The specification is accompanied by drawings, in which:

Fig. 1 is a section taken in elevation through a five-plate condenserembodying features of my invention;

Fig, 2 is a plan view of the same;

Fig. 3 is a bottom view of the same;

Fig. 4 is a perspective view of the top plate;

Fig. 5 is a perspective view of one of the thin upwardly bowed lowerplates;

Fig. 6 is a perspective view of a staple for mounting the condenser on astrip;

Fig. 7 is a perspective view of a soldering lug support used with thelugs of the thin plates;

Fig. 8 is a perspective view of a spacer strip;

Fig. 9 is a perspective view of a mica film;

Fig. 10 is a perspective view of the, base with the staple secured tothe bottom thereof;

Fig. 11 is a side elevation showing a plurality of condensers secured toa mounting strip;

Fig. 12 is a bottom elevation of the same;

Fig. 13 is a plan view of a modification which may be used with acondenser having only two, or, at most, say, three plates;

Fig. 14 is a section illustrating the preferred method of assembling theparts of the condenser; and

Figs. 15 and 16 are graphs illustrating the tuning curves of twodifferent types of my improved condenser.

Referring to the drawings, and more particularly to Fig, l. thecondenser comprises an insulation base I2 which is preferably made ofceramic material. A plurality of exceedingly thin resilient condenserplates are mounted on base I2. In the present case, there are four such,plates numbered I4, I6, l8, and 20 respectively. Mica films are disposedtherebetween, these films being numbered I5, I'l, I9, and 2|. Alternateplates and films are eyeleted to the base near one edge of the base, andthe plates are bent downwardly at that edge and extended for soldering.Thus, in the present case, plates I6 and 20, and films l1 and 2 I, areall eyeleted near one edge of the base by means of the eyelet 22. Theplates I6 and 20 are bent downwardly against the edge of the base, as isindicated at 25. This prevents oscillation of the plates about theeyelet 22 so that a single eyelet is adequate. The soldering lugsprojecting from the downturned portions 24 are indicated at 26. Inasmuchas the plates are preferably made of exceedingly thin metal (having athickness of, say, threethousandths of an inch), I find it desirable toback up or reinforce the soldering lugs 26 by means of a generallysimilarly shaped lug 28 (see Fig. '7) struck of heavy metal, the upperend 30 of lug 28 being secured to the underside of base I2 by means ofthe eyelet 22.

In a similar way, the other or remaining plates and films are eyeletedto, the base near the opposite edge. More specifically, the plates I4and I8, and the films I5 and I9, ar eyeleted to base l2 means of theeyelet 32. Plates I4 and I8 are bent downwardly against the edge of basel2 and are extended to form the soldering lugs 34. These are backed upby a thick soldering lug 36 which, however, is formed integrally withthe thick top plate 38 of the condenser, as is hereinafter described,

The top plate 38 is preferably made of phosphor-bronze metal in order togive the same a permanent resiliency. The thin plates are alsopreferably made of phosphor-bronze, but in the case of these plates Ifind that springy brass is also satisfactory. The plate is so shapedthat it tends normally to rise upwardly against the restraininginfluence of adjusting screw 40. A washer 42 is preferably disposedbetween the head of the adjusting screw and the top plate 38. Theadjusting screw is threadedly received in a metallic bushing 44, thelower end of which is disposed beneath the base, and also preferablybeneath an attaching staple 46, while the upper end is riveted outwardlyin a recess 48 at the top of the base, as is indicated at 50.

The top plate 38 extends over the top of the condenser and is then bentdownwardly along the edge of the condensen'as is indicated at 52,following which it is bent inwardly beneath the bottom of the condenser,as is indicated at 54. In accordance with the present invention, the topplate is free of the eyelet 32, and it is solely the inwardly bentbottom portion 54 that is eyeleted to the base. Moreover, the solderinglug 36 is struck out of the top plate and bent outwardly and downwardlyaway from the base, it being attached to the top plate solely at thelower end of eyelet 32, and solely to the inwardly bent part 54. Withthis construction, bending of lug 36 has no effect on the position oftop plate 38. Lug 36 may be bent upwardly to horizontal position withoutmoving top plate 38 downwardly, and without robbing the top plate of anyof its natural resilience tending to cause opening of the same. The bendof lug 36 is limited to lug 36 and is prevented from being transmittedto the remainder of the top plate by the action of eyelet 32.

The construction of the top plate will be readily understood frominspection of Fig. 4 of the drawings showing the same in perspective.The top plate 38 is cut away at 56 to clear the adjusting screw. Theplate is bent downwardly at 52 and inwardly at 54. The inturned part 54is perforated at 58 to receive the eyelet. The soldering lug 36 isstruck from plate 38, as is indicated at B0. The plate is cut away allthe way down to the inturned part 54 and to a point immediately adjacentthe eyelet hole 58. The lug may, if desired, be necked at its point ofconnection to inturned part 54, this being indicated at 62. With thisconstruction, lug 36 may be bent without affecting the position of theplate in the slightest degree. Moreover, the cutting away of the sidewall 52 of the plate, as shown, provides a passage for the soldering lugextensions 34 of the subjacent thin plates, these coming outside thethick lug 36, as is clearly shown in Fig. 1.

The attaching staple 46 is best shown in Figs. 3 and 6. It comprises aflat portion with two legs or prongs 64 turned downwardly at the endthereof. The staple 46 is apertured at 66 to receive the bushing 44.Moreover, the ceramic base i2 is preferably molded with a recess eX-tending thereacross to receive the staple and thereby preventoscillation of the same about bushing 44. Similar recesses may beprovided for other parts of the condenser, and, referring I to Fig. 3,the final construction may be described as involving projections 68 and16 on the base, these projections being so shaped and dimensioned as toform a space between projections 10 for the inturned part 54 of the topplate; a space between projections 68 to receive the upper part 30 ofsoldering lug support 28; and a space between the inner ends of all fourprojections to receive the staple 46.

The staple is, of course, secured to the insulation base at the sametime that the bushing 44 is secured in place. Thus, referring to Fig.10, the insulation base l2 carries the staple 46 at its bottom, thisstaple being secured in place by riveting of the upper end of thebushing, as is indicated at 50.

The manner in which the staple is used to secure a row of condensers toa mounting strip will be clear from inspection of Figs. 11 and 12. Themounting strip 12 is provided with holes 14 to receive the lower ends ofthe bushings. The strip is also provided with smaller holes 16 toreceive the staple legs 64. The condensers are assembled on strip I2 bysimply passing the staple legs 64 through the holes 16 and thereuponbending the legs 64 toward one another, as is clearly shown in thedrawings. This is preferably done by means of a small hand-press orfoot-press and results in a tight and secure mounting of the condenseron the strip while requiring only a few seconds for the mountingoperation. It will be understood that the strip 12 may be a wide stripmade of insulation such as Bakelite, or may be a narrow strip made ofmetal, or, if desired, may be angle or channel metal, all in accordancewith the requirements or preferences of the manufacturer of the radioequipment using the condensers. The wide strip shown at Figs. 11 and 12is insulation because it bridges the opposite sides of the condenser.When using metal, the strip must be narrowed to avoid short-circuitingthe condenser. It may, for example, have a width and be disposed asindicated by the strip 13 shown in broken lines in Fig. 3. Contact withpart 54 is permissible, for the top plate is ordinarily grounded, and,in any event, there is a connection through the adjusting screw andstaple. However, contact with the part 30 must be avoided. It will alsobe understood that while only three condensers are shown on thedrawings, the strip may be provided with four or many more condensers,as desired.

The features of the invention so far described are applicable to a smallcondenser having only two plates, as well as to condensers having a muchlarger number of plates. When only two or three plates are provided, thetop plate may, if desired, be modified slightly, as shown in Fig. 13, inorder to increase the area of the top plate and thereby increase thecapacitance of the condenser. Specifically, referring to Fig. 13, itwill be seen that the top plate 38 is adjusted by means of a screwacting on a washer 42, all as was previously described. In Fig. 13,however, the plate 38' instead of ending at the washer 42, is extendedor projected, as is indicated at 80. The projection of the top plate iscut away at 82 to safely clear the eyelet 22, which is, of course, atopposite polarity. These extensions 80 are preferably not used when thecondenser is a multiple condenser having spacers between the plates,for, as will subsequently appear, the extensions 86 would in such caseinterfere with tight closing of the condenser and would ther foreprevent the attainment of desired maximum capacitance.

The construction of the thin plates will be evidentfrom inspection ofFig. 5. The plate is cut away at 04 to clear the adjusting screw. It isperforated at 86 to'receive the eyelet. It is bent downwardly at 24 tobear against the edge of the base. It is extended at 26 to provide asoldering ing. 1 'By extending each of the plates, it is unnecessary toconnect the plates at any other point thanat the soldering lug, and themica films may, therefore, be extended between the plates and eyeletedin position even though this tends to insulate plates of common polarityfrom one another. It is important to notice the upward bowing of theplate, as is indicated at 38. The plate is springy, and may, forexample, be phosphor-bronze, and this bowing of the plate tends to causethe condenser to open out when pressure of the adjusting screw isrelieved.

The mica film is illustrated in Fig. 9. It is a thin rectangular filmcut away at 90 to clear the adjusting screw and at 92 to receive theeyelet. The mica films, like the plates, are held at one end only, theopposite end being free and therefore not interfering with opening up ofthe condenser except as a result of its own resistance to bending. Thisis butslight, for the plates are only, say, one and one-half thousandthsof an inch in thickness. The metal plates are also exceedingly thin, butare, say, double this thickness, being,preferably, three-thousandths ofan inch in thickness. The metal plates open up despite the interposedmica films. In fact, the films help produce more opening of thecondenser than would otherwise take place. This will be apparent if itis kept in mind that the metal plates all curve upwardly or in the samedirection. The interposition of straight mica films between the curvedplates causes a wide separation of the plates when the plates arepermitted to curve at all, as by relieving the pressure of the adjustingscrew.

To efiectually prevent binding of the plates together when the adjustingscrew is tightened all the way down, and also, to help attain a desiredlow minimum capacitance for the condenser, I find it of great help toinitially space the plates apart at the eyelets. This may be done, forexample, by appropriately deforming the plates immediately at or aroundthe eyelet holes, but I believe it more satisfactory to use real spacersbetween the plates. These spacers are preferably formed of metal strip,say, brass, having a thickness greater than that of the condenser platesand the mica films. Specifically, .I prefer to use spacers having athickness of, say, six-thousandths of an inch, while using plates havinga thickness of three-thousandths of an inch, and films having athickness of one and one-half thousandths of an inch. A typical spaceris shown in Fig. 8. It comprises a tiny strip of brass 94 apertured at96 to receive the eyelet. Three such spacers are shown in Fig. 1, one atthe right hand side of the condenser between film I5 and plate I8; andthe other two at the left-hand side of the condenser, one at the bottomdirectly above ceramic base I2, and the other between film I1 and plate20. It will thus be seen that these spacers are disposed opposite thefree ends of the plates and ,films which are eyeleted at the oppositeend of the condenser. It will also be seen that successive spacers areeyeleted at opposite ends of the condensers.

The method of assembling the parts of the condenser may be explainedwith reference to Fig. 14 of the drawings. This figure will also behelpful in understanding the construction of the condenser. Thecondenser is assembled in inverted position. The eyelets 22 and 32 arefirst slipped over, retractable or disappearing pins I00 passingslidably through bottom anvils I02 which project upwardly from the baseof a suitable fixture secured in a small press. In the present case, asix-plate condenser is shown, rather than a five-plate condenser, asshown in Fig. 1. Films, plates, and spacers are dropped over the pinsI00 and the eyelets in proper sequence to build up the desiredcondenser. Specifically, film I04, then plate I06, and then spacer I00are dropped over eyelet 22. Then film IIO, plate H2, and spacer IIQ aredropped over eyelet 32. Next, film H6, plate H8, and spacer I aredropped over eyelet 22. Then film I22, plate I24, and spacer I26 areslid over eyelet 32. Then film I28 and bottom plate I30 are placed overeyelet 22. Base I2 is already provided with staple 46 and bushing 44,and this assembly is then placed over pins I00. Finally, the lug support28 and the inturned part 54 of top plate 38 are slid over the pins I00.It is important to note that at this time the top plate 38 projectsdownwardly and. even outwardly somewhat, there being a slight bend atthe point I32. This assembly is then squeezed together by the operatorby pushing the base downwardly in order to flatten out the condenserplates and to expose the upper ends. of the eyelets 22 and 32. The pressis then operated to cause a forcible descent of top pins or curlinganvils I34. These have projections I36 which push the disappearing pinsI00 downwardly out of the way and which themselves enter the eyelets.The upper ends of the eyelets are then spread and curled outwardly bythe curling surfaces I38. The force of the press rivets the partstightly together.

The top anvils rise out of the way, and the assembled condenser is thenremoved from the bottom anvils. The next step in-the assembly operationis to bend the plate 30 around over the top of the condenser, whereuponthe adjusting screw is passed through the plates and screwed into thethreaded bushing. The screw holds the top plate in position and, ofcourse, the natural resiliency of the top plate causes it to tend toopen out at all times.

Fig. 14 is interesting in showing how the alternate use of straightfilms with curved plates tends to cause a large separation or opening ofthe plates, thereby making possible a low minimum capacitance. Fig. 14is also interesting in showing a modification of the invention in whichthe bottommost plate I30 isa flat plate instead of an upwardly bowedplate. This construction is used when it is of paramount importance toobtain a minimum capacitance when the condenser is opened. The minimumcapacitance is obtained because of the increased spacing between a fiatbottom plate, such as plate I30, and an adjacent curved plate, such asplate I24. Consider, for example, the case of a three-plate condenser.If the bottom plate is a fiat plate, the middle plate a curved plate,and the top plate is the thick, self-opening plate, it is evident thatthe minimum capacitance will be greater than if two curved plates areused beneath the top plate. The flat bottom plate is also useful whenmaking a condenser which has only two plates.

The effect of the flat bottom plate in a multiple plate condenser may bedescribed by com- Bil parison of Figs. 15 and 16 of the drawings. Fig.l6 shows the capacitance curves for four, five, and six-platecondensers, using all curved plates. Fig. 15 illustrates the tuningcurves obtained when using a fiat bottom plate. It will be seen that theminimum is reduced from about 35 to 20 mmf. for the four-platecondenser, from about 60 to 40 mmf. for the five-plate condenser, andfrom about 100 to 60 mmf. for the six-plate condenser.

However, even the curves of Fig. 16 are impressive in showing theexcellent performance of my improved condenser, for a capacitance rangeof from 100 to 500, or from 60 to 400, or from 35 to 300, is readilyobtainable. Even more important, not only is this range obtainable, butthe condenser is usefully adjustable throughout the range, for thecurves are not too steep, even at the high capacitance end, for gradualadjustment. Heretofore, a tiny trimmer condenser of this character, madeto attain a maximum capacitance of, say 500 mmf., was so critical thatthe slightest opening of the adjusting screw would drop the capacitancefrom, say, 500 to 250 mmf., thus making the condenser too critical to beat all manageable in the high capacitance end of its capacitance range.The present condenser, on the contrary, is usefully and readilyadjustable throughout its capacitance range. I

It will be understood that it is primarily because of the use of thespacers 943 between the plates that the top plate 38 is preferably keptshort, as shown in Figs. 1 and 2, instead of being extended, as shown at80; in Fig. 13. When the adjusting screw is turned up tight, themaximum,

capacitance is obtained by a slight downward bending of the upper platesso that the plates are brought tightly together despite the spacers atthe ends of the plates. If a top plate with the projections til wereused with a multiple plate condenser having spacers, the plates couldnot be squeezed tightly together for maximum capacitance, because theprojections d8 would overlie the spacers and would be held upwardlythereby.

It is believed that the construction and method of assembly, as well asthe many advantages of my improved trimmer condenser, will be apparentfrom the foregoing detailed description thereof. It will also beapparent that while I have shown and described my invention in preferredforms, many changes and modifications may be made in the structuresdisclosed without departing from the spirit of the invention defined inthe following claims.

I claim:

1. A condenser comprising an insulation base, metal condenser platessecured thereon with dielectric films therebetween, one plate beingeyeleted to the base near one edge of the base and being bent downwardlyat that edge and extended for soldering, the other plate extending overthe base and downwardly around the opposite edge of the base and theninwardly beneath the bottom of the base, said inwardly bent bottomportion having the full width of the plate and being eyeleted to thebase and said top portion being free of the base, a soldering lugconnected to said inwardly bent bottom portion at a point adjacent theeyelet by means of a necked or weakened connection such that bending ofthe soldering lug does not cause bending of the top portion of theplate, and an adjusting screw passing through said plates and base.

2. A trimmer condenser comprising an insulation base, metal condenserplates secured thereon with mica dielectric films therebetween,alternate plates beingeyeleted to the base near one edge of the base andbeing bent downwardly at that edge and extending for soldering, and theother plates being eyeleted to the base near the opposite edge and beingbent downwardly at that edge and extended for soldering, an adjustingscrew passing through said plates and base, the top plate extending overthe base and downwardly around an edge of the base and then inwardlybeneath the bottom of the base, solely said inwardly bent bottom portionbeing eyeleted to the base, and a soldering lug struck from said topplate to a point adjacent the eyelet and bent downwardly away from thebase, the cutaway part of the top plate afiording passage for solderinglug extensions from subjacent plates.

3. A condenser comprising an insulation base, a plurality of condenserplates thereon, mica films disposed therebetween, alternate plates beingeyeleted to the base near one edge only of the base, the other platesbeing eyeleted to the base near the opposite edge only of the base, saidplates being eyeleted at one end only in order to be movable at theother or free end for adjust ment of the capacitance of the condenser, aplurality of spacing means between said plates at the eyeleted endsthereof, and an adjusting screw passing through said plates and base,the spacing means between the eyeleted ends insuring movement of thefree ends and consequent free opening of the condenser plates when thepressure of the adjusting screw is relieved.

4. A condenser comprising an insulation base, a plurality of resilientcondenser plates thereon, mica films disposed therebetween, alternateplates and films being eyeleted to the base near one edge only of thebase, the other plates and films being eyeleted to the base near theopposite edge only of the base, said plates being eyeleted at one endonly in order to be movable at the other or free end for adjustment ofthe capacitance of the condenser, a plurality of metallic spacing meansbetween said plates at the eyeleted ends thereof, said means beingthicker than the condenser plates and films, successive spacing meansbeing provided at opposite ends of the base, and an adjusting screwpassing through said plates and base, the spacing means between theeyeleted ends insuring movement of the free ends and consequent freeopening of the condenser plates when the pressure of the adjusting screwis relieved.

5. A trimmer condenser comprising an insulation base, a plurality ofresilient condenser plates thereon, mica films disposed therebetween,alternate plates and films being eyeleted to the base near one edge onlyof the base, the other plates and films being eyeleted to the base nearthe opposite edge only of the base, said plates being eyeleted at oneend only in order to be movable at the other or free end for adjustmentof the capacitance of the condenser, a plurality of metallic spacersalso eyeleted between said plates, said spacers being thicker than thecondenser plates and films, and being disposed beyond the free ends ofthe plates and films, so that successive spacers are provided atopposite ends of the base, and an adjusting screw passing through saidplates and base, the spacers between the eyeleted ends insuring movementof the free ends and consequent free opening of the condenser plateswhen the pressure of the adjusting screw is relieved.

6. A condenser comprising an insulation base, a plurality of resilientmetal condenser plates, thereon, alternate plates being eyeleted to thebase near one edge only of the base, and the other plates being eyeletedto the base near the opposite edge only of the base, said plate beingeyeleted at one end only in order to be movable at the other or free endfor adjustment of the capacitance of the condenser, a plurality of micafilms between said plates, spacing means between said plates at theeyeleted ends thereof, and an adjusting screw passing through saidplates and base for adjusting the capacitance of the condenser, at leastsome of said thin plates being bowed upwardly in order to effect aspreading of the plates when the pressureof the adjusting screw isrelieved, the spacing means between the eyeleted ends insuring movementof the free ends and consequent free spreading of the condenser plates.

7. A trimmer condenser comprising an insula-' tion base, a plurality ofresilient metal condenser plates thereon, said plates being made ofexceedingly thin spring metal except for the top plate which is made ofthicker metal, alternate plates being eyeleted to the base near one edgeonly of the base, and the other plates being eyeleted to the base nearthe opposite edge only of the base, mica films between said plates,alternate mica films being eyeleted at one edge and the intermediatefilms being eyeleted at the opposite edge of the base, said plates andfilms being eyeleted at one end only in order to be movable at the otheror free end for adjustment of the capacitance of the condenser, aplurality of metallic spacers also eyeleted between said plates, saidspacers being thicker than the condenser plates and films and beingdisposed at the free ends of the plates and films so that successivespacers are provided at opposite ends of the base, and an adjustingscrew passing through said plates and base for adjusting the capacitanceof the condenser, at least some of said thin plates being bowed upwardlyin order to efiect an opening or spreading of the plates when thepressure of the adjusting screw is relieved, the spacers between theeyeleted ends insuring movement of the free ends and consequent freeopening of the condenser plates.

8. A condenser comprising an insulation base, metal condenser platessecured thereon with dielectric films therebetween, said plates beingmade of thin springy metal except for the top plate which is made ofcomparatively thick metal, alternate plates being eyeleted to the basenear one edge only of the base, the other plates being eyeleted to thebase near the opposite edge only, said plates being eyeleted at one endonly in order to be movable at the other or free end for adjustment ofthe capacitance of the condenser, an adjusting screw passing throughsaid plates and base, the top plate extending over the base anddownwardly around an edge of the base, and then inwardly beneath thebottom of the base, solely said inwardly bent bottom portion beingeyeleted t0 the base, and a soldering lug connected to said inwardlybent bottom portion at a point adjacent the eyelet by means of a neckedor weakened connection such that bending of the soldering lug does notcause bending of the top portion of the plate, at least some of saidthin plates being bowed upwardly in order to efiect a spreading of theplates when the pressure of the adjusting screw is relieved.

9. A trimmer condenser comprising an insulation base, metal condenserplates secured thereon with mica dielectric films therebetween, saidplates being made of exceedingly thin springy metal except for the topplate which is made of comparatively thick metal, alternate plates beingeyeleted to the base near one edge only of the base and being bentdownwardly at that edge and extended for soldering, the other platesbeing eyeleted to the base near the opposite edge only and being bentdownwardly at that edge and extended for soldering, mica films betweensaid plates, alternate films being eyeleted at one edge and theintermediate films being eyeleted at the opposite edge of the base, saidplates and films being eyeleted at one end only in order to be movableat the other or free end for adjustment of the capacitance of thecondenser, an adjusting screw passing through said plates and base, thetop plate extending over the base and downwardly around an edge of thebase, and then inwardly beneath the bottom of the base, solely saidinwardly bent bottom portion being eyeleted -to the base, and asoldering lug struck from said top plate to a point adjacent the eyeletand bent downwardly away from the base, the cutaway part of the topplate affording passage for soldering lug extensions from subjacentplates, at least some of said thin plates being bowed upwardly. in orderto effect a spreading of the plates when the pressure of the adjustingscrew is relieved.

10. A condenser comprising an insulation base, a plurality of resilientcondenser plates thereon with dielectric films therebetween, alternateplates being eyeleted to the base near one edge only of the base, theother plates being eyeleted to the base near the opposite edge only ofthe base, said plates being eyeleted at one end only in order to bemovable at the other or free end for adjustment of the capacitance ofthe condenser, a plurality of spacing means between said plates at theeyeleted ends thereof to insure movability of the free ends andconsequent spreading of the plates when pressures thereon is relieved,and an adjusting screw passing through said plates and base, the topplate extending over the base and downwardly around an edge of the base,and then inwardly beneath the bottom of the base, solely said inwardlybent bottom portion being eyeleted to the base, and a soldering lugconnected to said inwardly bent bottom portion at a point adjacent theeyelet.

11. A trimmer condenser comprising an insulation base, a plurality ofresilient condenser plates thereon with mica dielectric filmstherebetween, alternate plates and films being eyeleted to the base nearone edge only of the base, and the plates being bent downwardly at thatedge and extended for soldering, the other platesand films beingeyeleted to the base near the opposite edge only of the base, and theplates being bent downwardly at that edge and extended for soldering,said plates being eyeleted at one end only in order to be movable at theother or free end for adjustment of the capacitance of the condenser, aplurality of metallic spacers also eye- -leted between said plates, saidspacers being ill base, the top plate extending over the base anddownwardly around an edge of the base, and then inwardly beneath thebottom of the base, solely said inwardly bent bottom portion beingeyeleted to the base, and a soldering lug struck from said top plate toa point adjacent the eyelet and bent downwardly away from the base, thecutaway part of the top plate affording passage for soldering lugextensions from subjacent plates.

12. A condenser comprising an insulation base, a plurality of thinresilient condenser plates thereon, dielectric films disposedtherebetween, alternate plates being eyeleted to the base near one edgeonly of the base, the other plates being eyeleted to the base near theopposite edge only of the base, said plates being eyeleted at one endonly in order to be movable at the other or free end for adjustment ofthe capacitance of the condenser, a plurality of spacing means betweensaid plates at the eyeleted ends thereof, at least some of said thinplates being bowed upwardly in order to effect a spreading of theplates, the spacing means between the eyeleted ends insuring movement ofthe free ends and consequent free spreading of said plates, and aspecial top plate made of thick resilient metal, said top plateextending over the base and downwardly around an edge of the base, andthen inwardly beneath the bottom of the base, solely said inwardly bentbottom portion being eyeleted to the base, and a soldering lug connectedto said inwardly bent bottom portion at a point adjacent the eyelet.

13. A trimmer condenser comprising an insulation base, a plurality ofthin resilient condenser plates thereon, mica films disposedtherebetween, alternate plates and films being eyeleted to the base nearone edge only of the base, and the plates being bent downwardly at thatedge and extended for soldering, the other plates and films beingeyeleted to the base near the opposite edge only of the base, and theplates being bent downwardly at that edge and extended for soldering,said plates being eyeleted at one end only in order to be movable at theother or free end for adjustment of the capacitance of the condenser, aplurality of metallic spacers also eyeleted between said plates, saidspacers being thicker than the condenser plates and films and beingdisposed at the free ends of successive plates and films so thatalternate spacers are provided at opposite ends of the base, at leastsome of said thin plates being bowed upwardly in order to effect anopening or spreading of the plates, the spacers between the eyeletedends insuring movement of the free ends and consequent free opening ofsaid plates, and a special top plate made of thick resilient metal, saidtop plate extending over the base and downwardly around an edge of thebase, and then inwardly beneath the bottom of the base, solely saidinwardly bent bottom portion being eyeleted to the base, and a solderinglug struck from said top plate to a point adjacent the eyelet and bentdownwardly away from the base, the cutaway part of the top plateaffording passage for soldering lug extensions from subjacent plates.

14. In combination, a condenser, and a mounting strip for receiving oneor more of said condensers, said condenser comprising an insulationbase, a metallic bushing secured to said base, said bushing beinginternally threaded to receive an adjusting screw for the condenser, ametallic staple having an apertured bridge with spaced legs projectingtherefrom, said staple being secured to the bottom of said condenser bymeans of said bushing passing through said aperture, said mounting striphaving spaced holes receiving the spaced legs of said staple.

15. In combination, a trimmer condenser, and a mounting strip forreceiving one or more of said trimmer condensers, said trimmer condensercomprising an insulation base, a metallic bushing secured to said base,said bushing being internally threaded to receive an adjusting screw forthe condenser, a metallic staple secured to the bottom of said trimmercondenser by means of said bushing, the base of said condenser beingrecessed to receive said staple and to prevent oscillation thereof, saidmounting strip having spaced holes receiving the legs of said staple.

16. In combination, a condenser, and an elongated mounting strip forreceiving a plurality of said condensers arranged side by sidetransversely of said mounting strip, said condenser comprising aninsulation base, a metallic staple having an apertured bridge withspaced bendable legs projecting therefrom, the bridge on said staplebeing secured to the bottom of said condenser by means of a part of saidcondenser structure passing through said aperture, said mounting striphaving holes for receiving the spaced legs of the staple, and said legsbeing bent on the side of the strip opposite the condenser in order tofasten the condenser in position on the strip.

17. In combination, a condenser, and an elongated mounting strip forreceiving a plurality of said condensers, said condenser comprising aninsulation base, a metallic staple having an apertured bridge withspaced bendable legs projecting therefrom, the bridge on said staplebeing secured to the bottom of said condenser by means of a fastenerpassing through said aperture and having a head at its lower end largerthan the aperture, said mounting strip having a hole to receive theaforesaid head, and additional holes for receiving the spaced legs ofthe staple, said legs being bent on the side of the strip opposite thecondenser in order to fasten the condenser in position on the strip.

18. In combination, a condenser, and an elongated mounting strip forreceiving a plurality of said condensers, said condenser comprising aninsulation base, a metallic bushing secured to said base, said bushinghaving an enlarged head and being internally threaded to receive anadjus ing screw for the condenser, a metallic staple having an aperturedbridge with spaced bendable legs projecting therefrom, the bridge ofsaid staple being secured to the bottom of said condenser by means ofsaid bushing passing through said aperture, said mounting strip having ahole large enough to receive the head of the bushing and spaced holesreceiving the spaced legs of said staple, said legs being bent on theside of the strip opposite the condenser in order to fasten thecondenser in position on the strip.

19. In combination, a trimmer condenser and a mounting strip forreceiving one or more of said trimmer condensers, said trimmer condensercomprising an insulation base, a metallic staple having an aperturedbridge with spaced bendable legs projecting therefrom, the bridge ofsaid staple being secured to the bottom of said trimmer condenser bymeans of a fastener having a head at its lower end larger than theaperture,

the base of said condenser being recessed to re-- ceive said staple andto prevent oscillation thereof, said mounting strip having a hole forreceiving the aforesaid head of the fastener, so that the lid condenserwill rest flat on the mounting strip, said mounting strip havingadditional holes for receiving the spaced legs of the staple, said legsbeing bent on the side of the strip opposite the condenser in order tofasten the condenser in position on the strip.

20. In combination, a trimmer condenser and a mounting strip forreceiving one or more of said trimmer condensers, said trimmer condensercomprising an insulation base, a metallic bushing secured to said base,said bushing having an enlarged head at the bottom and being internallythreaded to receive an adjusting screw for the condenser, a metallicstaple having an apertured vent oscillation thereof, said mounting striphaving a hole for receiving the aforesaid head of the bushing, saidmounting strip having additional holes for receiving the spaced legs ofthe staple, I

said legs being bent on the side of the strip opposite the condenser inorder to fasten the condenser in position on the strip.

JOSEPH A. FLANZER.

